To extract an individual file from a mksysb on tape:
# restore -s4 -xqvf /dev/rmt0.1 /my/filename
Example:
restore -s4 -xqvf /dev/rmt0.1 ./etc/passwd
# restore -s4 -xqvf /dev/rmt0.1 /my/filename
Example:
restore -s4 -xqvf /dev/rmt0.1 ./etc/passwd